• The adult Aedes mosquito population has climbed 26 per cent since September
• In August and September, the dengue incidence rate for residents of landed homes is about six times higher than those in HDB flats
• This could be due to larger surface areas found in landed compounds and structures such as roof gutters
• NEA urged residents of landed houses to take extra measures to remove mosquito breeding habitats

SINGAPORE — The number of dengue cases in Singapore remains high, with the adult Aedes aegypti mosquito population, which transmits the dengue virus, increasing over seven consecutive weeks, the National Environment Agency (NEA) said on Friday (Oct 30).

The agency also singled out landed houses as having a markedly higher incidence of dengue cases and Aedes mosquito breeding compared to private apartments and public flats.

In a media release on Friday, NEA said that as of Thursday, the total number of dengue cases this year stood at 32,806.

This is more than double the 15,998 dengue cases recorded for the whole of 2019.

It is also well above the 22,170 cases reported in 2013, the largest dengue outbreak in Singapore’s history at that time.

The other bad news is, NEA had detected a 26 per cent increase in the adult Aedes mosquito population since the beginning of September.

However, the 565 dengue cases reported last week is about 5 per cent lower than the week before, and the rate of decline in cases has slowed, the agency added.

DENGUE INFECTIONS AMONG RESIDENTS OF LANDED HOUSING HIGHER THAN FLATS

NEA said that the dengue incidence rate for those living in landed residential property was estimated to be about 820 per 100,000 residents in August and September.

This figure is about six times higher than the incidence rate for residents in Housing and Development Board (HDB) flats. It is also about three times higher than the incidence rate for residents of private apartments.

From January to September this year, the number of dengue cases in landed houses also accounted for about a quarter of the total number of about 30,430 dengue cases in Singapore.

This is proportionally higher than the percentage of landed residential property in Singapore, NEA said. Figures from the Department of Statistics Singapore showed that landed properties accounted for 5 per cent of residential households last year.

WHY MORE DENGUE CASES IN LANDED HOUSES?

NEA said that landed houses are more vulnerable to mosquito breeding than private apartments or HDB flats due to the larger surface areas.

The greater variety of structures and receptacle types within landed residential homes is also conducive for harbouring mosquito breeding habitats.

Besides the usual domestic and ornamental containers and flower pot plates found in most homes, mosquitoes also breed in water fountains, roof gutters and drains within the compounds of landed estates, NEA noted.

It said that while an August poll conducted by government feedback portal Reach showed that residents of landed houses were the most concerned about the dengue situation, fewer than half of the residents polled said that they had cleared blockages in their roof gutters and drains or put Bti larvicide to kill mosquito larvae in them in the previous week.

NEA urged residents of landed homes to go beyond the regular measures to reduce breeding habitats such as over-turning pails and also:

• Turn over containers and store them under shelter when unused

• Cover water storage containers

• Scrub the interior surface of fountains to remove attached mosquito eggs

• Clear roof gutters and drains within the compound

• Add Bacillus thuringiensis israelensis (Bti) larvicide to stagnant water bodies that cannot be removed

DENGUE CLUSTER UPDATE

In an update on dengue clusters, NEA said that there were 162 clusters reported as of Thursday, 15 fewer than the previous week.

Clusters at Changi Road, Bishan Street 11, Carpmael Road and May Road were also closed last week.

Overall, 94 per cent of the 2,819 dengue clusters reported since the start of this year had been closed.

Still, the agency warned that the high number of weekly dengue cases, coupled with the increasing Aedes mosquito population, may lead to another surge in dengue cases in the coming months.

“NEA and our partners in the Inter-Agency Dengue Task Force have thus kept up inspections at dengue cluster areas, and maintained a high tempo of preventive inspections for mosquito breeding and dengue cluster operations, in order to further slow down dengue transmission,” it said.